The present invention relates to a vacuum cleaning tool that is adapted to be connected to the vacuum hose of a vacuum cleaning apparatus. A brush roller is disposed in a brush chamber of a housing, with bristles of the brush roller projecting through a vacuum slot formed in the base plate of the housing. An air turbine having blades rotatably drives the brush roller, with the air turbine being provided in a turbine chamber of the housing. Disposed between the brush chamber and the turbine chamber is a pivotable guide member for the suction air stream that is to act upon the air turbine, whereby in a first pivot position, the operating position, the suction air stream is directed essentially tangentially against the air turbine for achieving a high drive power.
A vacuum cleaning tool of this type is known from DE 42 29 030 A1. For mechanically cleaning a textile floor covering, a brush roller is disposed in the housing of the vacuum cleaning tool; the bristles of the brush roller project through a vacuum slot. The brush roller is driven via a belt drive by an air turbine, which is acted upon by the suction air stream. In so doing, the air turbine makes available an adequate drive power in order to ensure a powerful rotation of the brush roller, and hence a satisfactory cleaning, even on a long-pile floor covering.
Unfortunately, when the vacuum cleaning tool is raised from the surface of the floor that is to be cleaned, the danger exists that the user might reach into the rotating brush roller, which under unfavorable conditions can lead to injuries. A slowing down or shutting off of the drive of the brush roller is therefore provided in case the vacuum cleaning tool is raised from the floor. For example, when the tool is raised from the floor a bypass opening can be opened, as a result of which the suction air stream that is directed through the guide member upon the air turbine is reduced. During operation, a sealed closing off of the bypass air opening must be ensured so that the working power of the brush roller is not reduced in an uncontrolled manner due to an uncontrolled bypass air stream.
If to reduce the turbine power in a no-load state of the vacuum cleaning tool the connector is closed off by a cap, the driving suction air stream is interrupted; however, in so doing a considerable increase in noise of the vacuum cleaning tool must be tolerated. The forces required with an operating cleaning apparatus for opening the cap are, due to the high vacuum, considerable, so that such an arrangement must be embodied in such a way as to withstand high mechanical loads.
It is therefore an object of the present invention to improve a vacuum cleaning tool of the aforementioned general type so that the drive power of the turbine can be reduced with straightforward means when the vacuum cleaning tool is raised from the floor.